Multiple-Stimuli Responsive Bioelectrocatalysis Based on Reduced Graphene Oxide/Poly(N-isopropylacrylamide) Composite Films and Its Application in the Fabrication of Logic Gates

Abstract

In the present work, reduced graphene oxide (rGO)/poly(N-isopropylacrylamide) (PNIPAA) composite films were electrodeposited onto the surface of Au electrodes in a fast and one-step manner from an aqueous mixture of a graphene oxide (GO) dispersion and N-isopropylacrylamide (NIPAA) monomer solutions. Reflection-absorption infrared (IR) and Raman spectroscopies were employed to characterize the successful construction of the rGO/PNIPAA composite films. The rGO/PNIPAA composite films exhibited reversible potential-, pH-, temperature-, and sulfate-sensitive cyclic voltammetric (CV) on-off behavior to the electroactive probe ferrocenedicarboxylic acid (Fc(COOH)2). For instance, after the composite films were treated at -0.7 V for 7 min, the CV responses of Fc(COOH)2 at the rGO/PNIPAA electrodes were quite large at pH 8.0, exhibiting the on state. However, after the films were treated at 0 V for 30 min, the CV peak currents became much smaller, demonstrating the off state. The mechanism of the multiple-stimuli switchable behaviors for the system was investigated not only by electrochemical methods but also by scanning electron microscopy and X-ray photoelectron spectroscopy. The potential-responsive behavior for this system was mainly attributed to the transformation between rGO and GO in the films at different potentials. The film system was further used to realize multiple-stimuli responsive bioelectrocatalysis of glucose catalyzed by the enzyme of glucose oxidase and mediated by the electroactive probe of Fc(COOH)2 in solution. On the basis of this, a four-input enabled OR (EnOR) logic gate network was established.

A Resettable Keypad Lock with Visible Readout Based on Closed Bipolar Electrochemistry and Electrochromic Poly(3‐methylthiophene) Films

“…Our previous work showedt hat the majority of the film contents wasr GO insteado fG O. [8] The characterization and confirmation of the rGO films electrodepositedo nthe electrode surface werealso reported in our previous work. [8] When 3-methylthiophene (MT) in ACN containing BMI-PF 6 was electropolymerized into PMT on the surfaceo fI TO/rGO electrodes by CV,t he oxidation peak at about 0.6 Vi ncreased with the CV cycles (see the Supporting Information, Figure S2 B), because the electroactiveP MT could be electrochemically oxidized to its cationic states,t hat is, polaron (radical cation) and bipolaron (dication).…”

“…[8] The characterization and confirmation of the rGO films electrodepositedo nthe electrode surface werealso reported in our previous work. [8] When 3-methylthiophene (MT) in ACN containing BMI-PF 6 was electropolymerized into PMT on the surfaceo fI TO/rGO electrodes by CV,t he oxidation peak at about 0.6 Vi ncreased with the CV cycles (see the Supporting Information, Figure S2 B), because the electroactiveP MT could be electrochemically oxidized to its cationic states,t hat is, polaron (radical cation) and bipolaron (dication). [9] Considering that the thicker PMT films would take more time to be doped/dedoped by anions with the corresponding color change, two CV cycles were chosen as the optimal number of cycles in the electropolymerization in this work.…”

“…The electrodeposition of rGO was performed with CV scans between À0.1 and À1.2 Va t0 .1 Vs À1 for 4cycles in a0 .1 mg mL À1 GO dispersion at pH 7.0 according to our previous report. [8] Our previous work showed that the majority of the film contents was rGO instead of GO. The characterization and confirmation of the rGO films electrodeposited on the electrode surface were also reported in our previ- Figure 6.…”

“…ous work. [8] The obtained transparent ITO/rGO electrodes were cleaned with water to remove the unreacted chemicals, and then blow-dried with N 2 before being used.…”

Interfacing nanomaterials for bioelectronic applications

“…119 Even though biocatalytic reactions are not really programmed, all interactions are defined in terms of programming language, which is crucial for initial steps. In this work, Boolean logic, which express the basic language of Boolean algebra using physical implementation of logic functions, was used to define biocomputing systems.…”